Does the DB and DC plan combination have to pass a comparability test from a rights and features perspective in order to permissively aggregate?

For instance DC plans can take a lump sum at termination of employment whereas a DB plan can only do it at early retirement and retirement?

Would this be a failure in the “features”?

For a start, see 1.401(a)(4)-9(b)(3) and 1.401(a)(4)-4(d)(4) and (5).

I know of no reason a DB plan can't pay an optional lump sum at termination.